This invention relates to photoacoustic spectroscopy, and more particularly, to photoacoustic spectroscopy (PAS) system for remote sensing of explosives and toxic chemicals.
In recent years, the dangers arising from possible terrorist attacks have become more imminent. New security systems have been installed at airports. Train stations and many bus depots have increased security. Government facilities and many commercial establishments have greatly increased security. Homeland Security and other government agencies and various companies have implanted new security measures and are looking for improved security systems and techniques.
It is desirable to remotely detect explosives, toxic chemicals, harmful biological agent, and other hazardous material so that the detected explosives, toxic chemicals, harmful biological agent, and other hazardous material can be safely removed and destroyed.
The technical difficulties of detecting explosives are: (1) most explosive have very low vapor pressure and, therefore, give poor signal-to-noise ratio, and (2) explosives typically are carried in concealed containers which further reduces their vapor concentration.
Over the years various systems and techniques (processes and methods) have been developed or suggested to detect explosives, toxic chemicals, harmful biological agent, and other hazardous material. Such prior systems and techniques to detect explosives, toxic chemicals, harmful biological agent, and other hazardous material, have met with varying degrees of success.
It is, therefore, desirable to provide an improved photoacoustic spectroscopy system and technique for remote sensing of explosives and toxic chemicals, which overcomes most, if not all of the preceding problems.